Process of manufacture of blanc fixe



UNITED STATES PATENT OFFICE.

GRANVILLE MOORE, OF SAN FRANCISCO, CALIFORNIA.

PROCESS OF MANUFACTURE OF BLANC FIXE.

No Drawing.

The object of the invention is to provide a pure white blanc fixe(precipitated barium I sulfate).

Blane fixe has several trade uses, such as pigments, coatings for papersand the like, and. its-value is very largely determined by the degree ofpurity. When it is of pure white quality it commands a price greatly inexcess of those grades in which impurities occur.

The principal impurities in crude barytes are silica and silicates andsulfids of iron, lead and copper. My improved treatment contemplates theseparation of these impurities to leave a pure barium sulfate possessingood covering qualities.

y process is as follows The crude barytes ground to any suitablefineness, ref rably 200 mesh, is mixed with sodium 0 lor d and alkalimetal nitrates or carbonates or' both, and the mixture is then subjectedto fusion.

After fusion of the barytes in the sodium chlorid flux, either with orWithout the addition of other fluxes such as alkali metal nitrates orcarbonates or both, the fused mass is quickly chilled either bydischarging it, in a molten condition, into water, or u on some coolsurface. The sodium chlori is used as a solvent for the barium sulfateand a the alkalimetal nitrates and carbonates form arated from slag bypermitting the fusion Specification of Letters Patent.

has good covering qualities.

Patented Aug. 23, 1921.

Application filed August 13, 1919. Serial No. 317,384.

to flow through intermediate settling pots before discharging it intothe water. I The following equations are given as illustrations of thereactions involved, but they will vary depending upon the percentages ofimpurities in the crude barytes. 4

1 'SiO +Na Co '=-Na,SiO +CO 2 FeSiO+N a CO :Na FeSiO, C02. 3 FeS+2NaNO+SiO.=

4 PbS -f-QNaN If an excess of carbonates is used, some barium carbonatewill be formed. This would then remain with the precipitated bariumsulfate formed later in the process, and would have to be converted tosulfate by sulfuric acid.

After discharging water, the pure barlum sulfate slime is filtered outand washed free from salt. The salt is thus recovered for furtherfusions and a purebarium sulfate obtained which I claim a definiteadvantage in that step of my process in which the fused mass isdischarged into cold water. mitted to cool slowly, crystalline bariumsulfate is obtained when the sodium chlorid is dissolved out, and thiscrystalline product has very little covering quality as a paint.However, when the fused mass is submitted to the shock incident to itsprecipitation in the cold water, an explosion efi'ect takes place, whichproduces a pure barium sulfate possessing excellent covering qualities.

Having thus described my invention what I claim as new and desire tosecure by Letiters Patent of the United States is as folows:-

1. The method of! producing bl'anc fixe which consists in mixing crudebarytes with sodium chlorid and alkali metal nitrates and carbonates andthen subjecting the mixture to fusion, then chilling the fused mass bydischarging it into cold water.

2. That step in the process of making If it is per-' the fused mass intoblanc fixe which consists in subjecting a barytes with sodium chloridand alkali fused mass containing barytes, sodium metal nitrates,subjecting the mixture to chlorid and alkali metal nitrates and canfusion, then chilling the fused mass by dis- 10 bonates to a shocktreatment by precipitatcharging it into cold Water. 5 ing said mass intocold water. In testimony whereof I aflix my signature.

8. The method of producing blanc fixe which consists of mixing finelydivided crude GRANVILLE MOORE.

